I have to say, I really liked this. The rhythm was great, and the pattern worked really well. It did make the ending seem a little blunt though, but it definitely had an impact. I also loved the first stanza, moving from thought to conclusion in so few words. You can't go wrong with this scheme, and it definitely worked. Great job! :)

First thing that springs to mind about this poem is it's very ambiguous. Nothing is certain about what is actually going on, which is in a way interesting as it allows the reader to project their own ideas onto the poem (personally I was getting strong hints of Jane Eyre as I read it, hmm).

I liked the last line as it brings in a personal element to the strange, nightmarish atmosphere. It might have been nice to have a little more elaboration (for instance, the mention of 'injections' is very mysterious) but obviously with the length and restrictive rhyme scheme this would be difficult!

The scheme seems a tough one to stick to over 5 stanzas so it's an achievement you managed to do it without it feeling particularly contrived - first read it flowed well, there were no lines that seemed obviously forced to fit with the rhyming pattern (last line of stanza four perhaps, but not overly so). You could maybe have found a more descriptive word than 'stupid' for the second (but again, this could be referring to anything so it's hard to make a judgement). I think the last stanza is my favourite, which is good as it should leave an impact :)

Overall, an interestingly mysterious poem with a brave rhyme scheme (I'm a wuss and stick to free verse :L).